The following job has been done by Stewie S., from Australia. Stewie is passionate about making saws and wooden planes. He authorized me to publish his pics in order to collaborate to blog and increase content availability. Thank you Stewie!
After 12 months of making backsaws as well as trialing different saw handles it was time for me to consolidate my restrict my work to 3 to 4 designs only. This following handle shape is for backsaws 12" and above. I have attached photos that show you each of the important steps involved from start to finish.
I hope you find the following information of some help especially to those who may have considered giving backsaw making a go.
Here you can view the handle as its shaped to design paper template. Some rounding to the handle as well as the inside of the finger hole has also been completed. I prefer to drill and fit the saw screws very early into the work. 
The 12" x 3" saw plate shaped and fitted within the handle. 
To help me mark the harback mortise within the handle I prefer to use a spare length of hardback which is fitted to the toothline. The use of upper and lower hardbacks locks the external saw plate in the same parrallel alignment to that within the handle. A good method to use if you want to keep the saw plate nice and straight along the toothline. 
To clean out the hardback mortise on the handle I like to use a variety of hand tools that also include planemaker floats. 
In this photo you can see that the brassback has been cut to length, rounded off at the toe, and secured to the handle. The bottom line of the saw plate is also nice and straight. 
The shaping of the handle is also nearly completed. 
Hear you can see the final stages of sharpening the saw teeth. I chose to go for a 12 tpi. rip tooth for this backsaw. The saw vise clamping length was modified from its original 9 " to a new 23.5 " 
The final look of the backsaw. The Tas.Tiger Myrtle chosen for the handle came up a treat. I only use 0000 steel wool between each coat of wood sealer and shellac. Another unique saw to add to my collection. Regards; Stewie
I hope you find the following information of some help especially to those who may have considered giving backsaw making a go.
Here you can view the handle as its shaped to design paper template. Some rounding to the handle as well as the inside of the finger hole has also been completed. I prefer to drill and fit the saw screws very early into the work. The 12" x 3" saw plate shaped and fitted within the handle. To help me mark the harback mortise within the handle I prefer to use a spare length of hardback which is fitted to the toothline. The use of upper and lower hardbacks locks the external saw plate in the same parrallel alignment to that within the handle. A good method to use if you want to keep the saw plate nice and straight along the toothline. To clean out the hardback mortise on the handle I like to use a variety of hand tools that also include planemaker floats. In this photo you can see that the brassback has been cut to length, rounded off at the toe, and secured to the handle. The bottom line of the saw plate is also nice and straight. The shaping of the handle is also nearly completed. Hear you can see the final stages of sharpening the saw teeth. I chose to go for a 12 tpi. rip tooth for this backsaw. The saw vise clamping length was modified from its original 9 " to a new 23.5 " The final look of the backsaw. The Tas.Tiger Myrtle chosen for the handle came up a treat. I only use 0000 steel wool between each coat of wood sealer and shellac. Another unique saw to add to my collection. Regards; Stewie 